/*
 * Copyright (c) 2011-2015 Pivotal Software Inc., Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.camunda.bpm.extension.reactor.projectreactor;

import java.util.concurrent.TimeUnit;

/**
 * A Resource is a component with an active state, generally consuming hardware capacities (memory, cpu, io).
 * The interface does not contract the creation of the resource but the closing methods, a graceful shutdown and an
 * enforced shutdown.
 *
 * @author Stephane Maldini
 * @since 2.0
 */
public interface Resource {

  /**
   * Determine whether this {@code Resource} can be used.
   *
   * @return {@literal true} if this {@code Resource} is alive and can be used, {@literal false} otherwise.
   */
  boolean alive();

  /**
   * Shutdown this active {@code Resource} such that it can no longer be used. If the resource carries any work,
   * it will wait (but NOT blocking the caller) for all the remaining tasks to perform before closing the resource.
   */
  void shutdown();


  /**
   * Block until all submitted tasks have completed, then do a normal {@link #shutdown()}.
   */
  boolean awaitAndShutdown();

  /**
   * Block until all submitted tasks have completed, then do a normal {@link #shutdown()}.
   */
  boolean awaitAndShutdown(long timeout, TimeUnit timeUnit);

  /**
   * Shutdown this {@code Resource}, forcibly halting any work currently executing and discarding any tasks that
   * have not yet been executed.
   */
  void forceShutdown();

}
